In electronic devices used for a server, a central processing unit of a personal computer, or the like, in order to improve the performance, microfabrication of a semiconductor element has advanced, and the heat generation amount per unit area has increased. As a result, heat dissipation of the electronic device is an important problem. Therefore, a structure in which a heat spreader made of a material having high thermal conductivity such as copper is disposed via a thermal interface material provided on a semiconductor device is being used.
The thermal interface material must have high thermal conductivity and, in addition, must have a characteristic being in contact with the fine irregularities of the surface of a heat generation source and a heat spreader.
A thermal conduction sheet is being sought that uses a linear structure made of carbon represented by a carbon nanotube as the thermal interface material. The carbon nanotube is a material having not only very high thermal conductivity (1500 W/m·K) but also excellent in flexibility and heat resistance, and has high potential as a heat dissipating material.
As a thermal conduction sheet using a carbon nanotube, a thermal conduction sheet in which a filling layer made of a thermoplastic resin is provided among a plurality of linear structures made of carbon represented by a carbon nanotube is being presented.    Japanese Laid-open Patent Publication No. 2010-118609